Sub-surface nanometrology of semiconductor wafers and graphene quality assessment via terahertz route

Abstract

Modern integrated circuit (IC) packaging faces challenges for higher speed in a smaller dimension achieved due to the 10 nm or smaller process node. While ICs are being packaged in 3D format, it is often not possible to measure features and/or defects in a non-destructive route. This paper reports a technique for nanometrology using bigger wavelengths such as those within the terahertz range. Practical measurements of dot pattern and other patterns on a 3D chip under the surface have been carried out. Two graphene have been imaged for quantifying the number of layers in the exfoliate also the thickness of each graphene sheet in the exfoliate. The results check out well compared to the standard techniques such as the SEM. In addition, a criterion for graphene’s quality assessment in terms of direct measurement of number of sheets in an exfoliate has been proposed. Thus, the nanometrology reported here, is a versatile tool for nanoscale measurements.